I have form altered the backup and migrate quick backup screen (admin/config/system/backup_migrate) and added a text field. I'd like to use the value of the field to create a new node just before the backup is done. I found a way to "hook" backup and migrate just before it performs a backup, which is great. However, I need to get $form_state['values']['my_value'] and pass that to my function that creates a new node. I can't figure out how to get that passed to the pre_backup() inside the extended class backup_migrate_filter.

Most excellent! I should have mentioned that I did end getting the clues I needed from a friend and I added my function to the submit handler. Thank you for replying! An upvote for you, sir.
– jonathanbellSep 10 '15 at 16:50